168 STUDIES OF TREES 



in many cases, work on the under side of the branch so that 

 the man in the tree looking down cannot see its dangerous 

 condition. 



5. A dead limb with the bark falling off indicates that it 

 died at least three months before and is, therefore, less 

 safe than one with its bark tightly adhering to it. 



6. Branches are more apt to snap on a frosty day when 

 they are covered with an icy coating than on a warm 

 summer day. 



7. Always use the pole-saw and pole-shears on the tips 

 of long branches, and use the pole-hook in removing dead 

 branches of the ailanthus and other brittle trees where it 

 would be too dangerous to reach them otherwise. 



8. Be sure of the strength of a branch before tying an 

 extension ladder to it. 



STUDY IV. TREE REPAIR 



Where trees have been properly cared for from their 

 early start, wounds and cavities and their subsequent 

 elaborate treatment have no place. But where trees have 

 been neglected or improperly cared for, wounds and cavities 

 are bound to occur and early treatment becomes a necessity. 



There are two kinds of wounds on trees: (1) surface 

 wounds, which do not extend beyond the inner bark, and 

 (2) deep wounds or cavities, which may range from a small 

 hole in a crotch to the hollow of an entire trunk. 



Surface wounds: Surface wounds (Fig. 116) are due 

 to bruised bark, and a tree thus injured can no longer pro- 

 duce the proper amount of foliage or remain healthy very 

 long. The reason for this becomes very apparent when 

 one looks into the nature of the living or active tissue of a 



